Babies devote the majority of their time to sleeping, but until now, little has been known about the links between sleep and the unprecedented levels of growth and development that take place during their first year of life.

The youngsters were shown how to remove and manipulate a mitten from a hand puppet and were given the opportunity to reproduce these actions after delays of four and 24 hours.

Infants who didn’t nap after learning were compared with age-matched infants who napped for at least 30 minutes within four hours of learning the target actions.

Only infants who napped after the learning activity remembered the target actions. Those who hadn’t napped showed no evidence of remembering the new information and behavior.

When baby gets sleepy

After a 24-hour delay children in the napping group also exhibited significantly better recall compared with infants in the no-nap group.

“These findings are particularly interesting to both parents and educationalists because they suggest that the optimal time for infants to learn new information is just before they have a sleep,” says Jane Herbert from the psychology department at University of Sheffield.

“Until now people have presumed that the best time for infants to learn is when they are wide-awake, rather than when they are starting to feel tired, but our results show that activities occurring just before infants have a nap can be particularly valuable and well-remembered.”

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The study also suggests that allowing flexible napping schedules in response to different daily schedules could help ensure optimal learning conditions for infants.

Naps that are shorter than 30 minutes don’t give babies enough time to consolidate their knowledge so it can be retained over the long term.

“Parents receive lots of advice about what they should and shouldn’t do with their baby’s sleep schedule,” Herbert says. “This study however examined learning opportunities around naturally occurring naps and shows just how valuable activities like reading books with young children just before they go down to sleep can be.”

The researchers will next look at whether sleep not only enhances the quantity of infants’ memory, for example how much is remembered, but also the quality of memory such as how the recollections are used.